Thursday, December 30, 2010

Even though Leonardo da Vinci is primarily thought of as a painter, he made many contributions to science. His greatest talent was in accurately observing and recording the world around him and most of his surviving work is mechanical, anatomical and architectural drawings and manuscripts. His main concern was always how things worked and he used his eyes to see how things were made and then record them in such a way as to make it clear as to how they functioned. For da Vinci, art was a tool for discovery and invention, whether it was to detail how the human hand works or to create a prototype of an airplane or helicopter.

Leonardo spent much time in Florence where he dissected bodies in the St. Maria Nuova hospital, recording the position and shape of organs as well as trying to figure out what they did by analyzing their structure. During his lifetime he worked on 30 bodies.

Leonardo da Vinci's design for an aerial screw.

He was also fascinated with the flight of birds and how humans could fly, drawing several human-powered flying machines. He saw air as a medium with properties similar to water, such as current. His drawings of pumps and screws show that he understood how these machines could interact with a fluid. Leonardo’s design of a helicopter was based on a screw that would propel itself upward through the air.

Leonardo was also the first to explain why there is a ghostly image of the full Moon whenever there’s a crescent Moon on the horizon at sunset. Astronomers call it Earthshine and Leonardo correctly attributed it to our own planet reflecting light back to us from the Moon. Yet Da Vinci’s legacy goes beyond his drawings and discoveries. He showed that inquisitiveness together with observation can reveal how things work, and how that information could be used in the creation of buildings, machines or inventions.

1) True or false: Da Vinci had a good understanding of fluid dynamics.

2) Most of Leonardo da Vinci’s surviving work is of ___________________________.

a) paintings b) sculptures c) drawings and manuscripts d) inventions

3) True or false: Leonardo dissected a few bodies to further his understanding of anatomy.

4) Many of Leonardo’s inventions were ______________________.

a) motor-driven flying machines b) based on observations in nature c) easily constructed at the time d) all of the above

5) Reflected light from Earth that is visible on the Moon’s night side is called __________.

Tuesday, December 21, 2010

As I write this tonight, mother nature is taunting me. Overhead there is a total lunar eclipse in progress and I’m missing it because it’s completely overcast and raining. Such is life. Lunar eclipses are fairly common, happening a couple times a year on average. But this one is different. It just so happens that this morning, December 21, is the beginning of winter solstice. A pure coincidence, but it means that the Moon will be at its maximum height in the sky to provide superb viewing of the eclipse. The last time that happened was in 1638.

The stages of a total lunar eclipse.

A lunar eclipse occurs when the Earth passes directly between the Sun and Moon, blocking the Sun’s light and casting a shadow on the Moon. Because the Moon is opposite the Sun, the Moon will always be full the night of a lunar eclipse. As the Moon progresses into the Earth’s shadow, it changes color from gray to orange or even red. This is because even though the Moon is in shadow, sunlight can still reach it indirectly by refracting through Earth’s atmosphere. Since our atmosphere filters out blue-colored light (that’s why the sky is blue), only light from the red/orange portion of the spectrum passes through and actually makes it to the Moon and this light is what we see during a total lunar eclipse. If the atmosphere has more particles in it, say from recent volcanic activity, for example, the Moon will take on a deeper shade of red.

Eclipses are said to be either umbral or penumbral. The word “umbra” is from the Latin word for “shadow” and this is what we call a total eclipse. Penumbra is Latin for “almost shadow” and this refers to a partial eclipse. The next opportunity we will have to see a total lunar eclipse here in the U.S. will coincide with a somewhat more dubious date—Tax Day—April 15, 2014.

1) True or false: A lunar eclipse occurs when the Moon passes between the Earth and the Sun.

3) True or false: The moon will appear redder if there has been recent volcanic activity.

4) Regarding winter solstice, which of the following is not true?

a) It occurs when the Earth’s axis is tilted farthest away from the sun. b) It signifies the first day of winter in the U.S. c) It occurs on the shortest day and longest night d) It occurs when the Earth is farthest from the Sun.

Wednesday, December 15, 2010

Density is the amount of mass per unit volume of a substance. The Greek mathematician and scientist Archimedes is credited with using the concept of density to determine whether or not a crown made for King Hiero was made of pure gold. Legend has it that the king thought his goldsmith was cheating him by substituting silver for some of the gold he was given to make the crown, so he asked Archimedes to test the crown without destroying it. Archimedes was stumped until one day when getting into his bath he caused the water to overflow. He realized that he could put a weight of pure gold equal to the weight of the crown into a bowl and add water until it was filled to the brim. Then when he removed the gold and put the crown in it would make the water overflow if it contained silver because silver is not as dense and therefore it would take up more volume. It’s said that upon this discovery, Archimedes ran through the street naked shouting “Eureka!” which means “I found it!” in Greek. No word on what happened to the goldsmith.

Osmium is the densest naturally-occurring element, being twice as dense as lead. In nature, osmium is found alloyed with platinum. Alloys of osmium and platinum are used where hardness and durability is needed such as electrical contacts or in the tips of fountain pens. The least-dense metal, lithium, is so light that it floats in water. But the record for the lightest solid is held by Aerogel which weighs only three mg per cubic centimeter, or about one tenth the density of the lightest Styrofoam!

Manufactured by JPL in Pasadena, California, it’s nearly transparent with a blue cast and is surprisingly sturdy. It’s made of pure silica but is 99.8% porous. It makes an excellent insulator—almost 40 times better than fiberglass. Aerogel was used on NASA’s Stardust Mission that returned to Earth in 2006 after a flyby with a comet. Its purpose was to collect dust particles for analysis back on Earth. These dust particles travel so fast that they would penetrate most solids and be vaporized—yet when the collide with Aerogel they are buried in the material and come to a relatively gradual stop so that they can be collected.

1) True of false: An alloy of gold and silver is less dense than pure gold.

2) The least-dense metal is __________________.

a) aluminum b) lithium c) silver d) Aerogel

3) True or false: Osmium is twice as dense as gold.

4) Which of the following is not true about Aerogel?

a) Aerogel is man-made b) Aerogel is very delicate c) Aerogel is lighter than Styrofoam by an order of magnitude d) Aerogel was made for NASA.

5) Archimedes shouted ___________ upon solving the puzzle of the king’s crown.

Tuesday, December 7, 2010

Hale Telescope. The light from HR8799 has beenmasked with the aid of a coronagraph.

We’re all familiar with the eight planets in our solar system, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, but did you know that since 1992 there have been hundreds of planets discovered outside our solar system? And that number is rapidly increasing with thousands of new planets waiting to be confirmed. Planets outside our solar system are called exoplanets.

Recent advances in telescope technology allow exoplanets to be seen directly, but it helps if the planet is very large, even larger than Jupiter, for example, and far from the star that it orbits so that it’s not lost in the glare. A relatively hot exoplanet that gives off infrared radiation is also easier to detect. In 2010, three exoplanets orbiting HR8799, a star 120 light-years away, were photographed using a portion of the Palomar Observatory’s Hale Telescope. This was the first time exoplanets were photographed using a relatively small telescope by attaching a coronagraph to it. A coronagraph blocks out the direct light from a star so that nearby objects—which would otherwise be hidden by the star’s glare—can be seen. The three planets are thought to be gas giants like Jupiter, but more massive. Most exoplanets, however, are indirectly detected. One method is measuring minute variations in a star’s velocity due to the gravitational tug a planet has on it. Exoplanets that orbit pulsars can be indirectly detected by measuring tiny changes in the pulses of radio waves that are emitted. This is how the first exoplanet was discovered.

Liftoff of NASA’s Kepler Spacecraft

aboard a Delta II Rocket.

Astronomers can also detect planets by observing a drop in a star’s brightness as a planet crosses directly in front of it. In 2009 NASA launched the Kepler Mission in an attempt to discover Earth-like planets using this method. Kepler’s space telescope will continuously monitor 145,000 stars looking for periodic changes in brightness that would indicate an exoplanet moving across the face of the star. Kepler’s goal is to find an Earth twin—similar in size and distance from its star so that water could exist in liquid form on its surface—thought to be essential for the formation of life. James Fanson, Kepler Project Manager at JPL in Pasadena, had this to say of the Kepler Mission: “Our team is thrilled to be a part of something so meaningful to the human race—Kepler will help us understand if our Earth is unique or if others like it are out there.”

Tuesday, November 30, 2010

In the hundred plus years since Einstein published his theory of relativity it has been put to the test many times. General relativity—Einstein’s theory of gravity—has been tested by measuring the apparent shifting of position of stars whose light passes near the sun during a solar eclipse (known as gravitational lensing, discussed here). It has also been used to explain the wobble in Mercury’s orbit around the Sun.

Special relativity, the theory that introduced the concept of spacetime, and from which Einstein derived his famous equation E=mc2, has also been tested—most famously by Michelson and Morley (discussed here) who confirmed that the speed of light is constant as Einstein predicted. Another aspect of special relativity—time dilation—has been confirmed by comparing the time on an atomic clock sent on an around-the-world airplane trip with one left behind. There is a very small difference between the time for the two clocks which agrees precisely with Einstein’s theory.

Now it looks like relativity may again be tested, this time by physicists working at CERN who have managed to create and trap small quantities of antimatter by using very powerful magnetic fields in devices known as Penning traps. The antimatter they’ve created is antihydrogen. A normal atom of hydrogen consists of a positively-charged proton bound to a negatively-charged electron. Antihydrogen, however, is made by binding a negatively-charged antiproton to a positively-charged electron or positron. According to Einstein’s theory, if scientists can collect enough antihydrogen to do a spectrum analysis, it should match the spectrum for hydrogen exactly. It’s a long shot that the spectrums will differ, but if they do it would leave many physicists in shock, and quite likely earn the team that discovers it a Nobel Prize.

Tuesday, November 23, 2010

Packed into a two-acre excavation site near Green River, Utah are hundreds, maybe thousands, of fossilized remains of a new dinosaur species discovered back in 2001: Falcarius utahensis.

This species lived about 125 million years ago during the early Cretaceous Period. Falcarius walked on two legs. Adults measured about four meters from head to tail and were well over a meter tall. They had sharp, curved, claws measuring up to 15 cm in length and were probably covered with hairy feathers. It’s thought that these creatures are one of the ancestors to modern-day birds.

Artistic rendering of a Therizinosaur, courtesy of Nobu Tamura.

Yet the most interesting aspect of these dinosaurs is that they are thought to have been omnivores. Dr. Scott Sampson, chief curator at the Utah Museum of Natural History and coauthor of a study on Falcarius published in the May 2005 issue of Nature, is quoted as saying that Falcarius “...is the missing link between predatory dinosaurs and the bizarre plant-eating Therizinosaurs.”

Evidence that it ate plants includes a large pelvis bone to support a larger intestinal tract that’s needed for digesting plants. Falcarius also had leaf-shaped teeth which were ideal for eating plant material. Yet—like Velociraptor—they had sharp, curved claws for hunting, so it’s thought that they also caught and ate small animals.The name Falcarius comes from Latin, and means sickle maker which aptly describes its unusual clawed limbs. The name may not be as catchy as T-Rex or Velociraptor but this dinosaur is definitely interesting.

1) True or false: Falcarius is thought to be an herbivore.

2) Falcarius is believed to have been covered with __________.

a) smooth skin b) scales c) fur d) hairy feathers

3) True or false: Falcarius had teeth that were well-suited for eating plants.

4) Falcarius is thought to be a missing link between carnivores and ____________.

Wednesday, November 17, 2010

Mesa Verde National Park, located near the southwest corner of Colorado, is home to some of the best-preserved ancient cliff dwellings in the world. The largest structure is called Cliff Palace. It was built by the Anasazi people—ancient ancestors of today’s Puebloans—over 750 years ago.

Recent studies reveal that Cliff Palace had 150 rooms and 23 kivas, or rooms used for religious ceremonies. It’s estimated that about 100 people lived at Cliff Palace. This is quite a departure from the typical cliff dwellings found at Mesa Verde National Park, which contain from one to five rooms each, with many of the single room structures being used for storage. Archaeologists believe that Cliff Palace was used mainly for religious ceremonies.

Looking at the size of the doorways in Cliff Palace one realizes just how small the Anasazi people must have been—an average man being about 163 cm (5’4”) tall, and an average woman being about 152 cm (5’0”) tall. The Anasazi’s life span was relatively short, partly because of an exceptionally high infant mortality rate. Sadly, about half of their children died before their fifth birthday, with most adults only living into their mid- to late-30s. One can only imagine the hardships they must have faced!

Cliff Palace is mainly constructed of sandstone, mortar and wooden beams. The Anasazi would collect hard river rocks and use them to shape the larger sandstone blocks for the bulk of their structures. For mortar, they used a mixture of soil, water and ash. They would fill the gaps in the mortar with smaller “chinking” stones to add stability to the walls. Then they painted the surface of the walls with colored plaster made from mud and clay.

Ansel Adams visited Cliff Palace in 1941 and published several spectacular photographs which can be viewed online at the National Archives website, along with his other photographs of our national parks: www.archives.gov/research/ansel-adams

1) True or false: Puebloans are the ancient ancestors of the Anasazi peoples.

Tuesday, November 9, 2010

A composite image of the Crab Nebula showing the X-ray (blue), and optical (red) images superimposed.

Within the depths of the Crab Nebula there lies a beast. It is an object that is only 19 km in diameter and emits pulses of radio waves at a rate of 30 times per second. These pulses are so powerful that they light up the entire nebula. This object is the remnant of a supernova explosion, one of the most energetic events in the entire universe. It’s a pulsar—a rotating neutron star. A star so dense that a teaspoon of it would have a mass about 900 times that of the Great Pyramid of Giza. It’s so dense that the atoms within it have collapsed in the gravitational crush to the point where electrons have been pulled into the nucleus converting protons into neutrons.

A pulsar creates a magnetic field a million times more powerful than earth’s. It also creates powerful beams of electromagnetic radiation emanating from its two poles. The reason that pulsars pulse is because they are rotating. As they rotate, we detect these jet of radiation at regular intervals, much in the same way that a lighthouse works.

Because a pulsar rotates about an axis that is not aligned with its magnetic poles, an observer will see regular pulses of radiation as the magnetic poles come in and out of sight.

The Crab Nebula pulsar was formed in the aftermath of the supernova explosion of 1054 AD and was recorded by Chinese and Arab astronomers at the time. For two years it was visible to the naked eye and at its peak it was the second brightest object in the night sky, being surpassed only by the moon. Thanks to these ancient astronomers this was the first recorded instance of a supernova explosion.

The first pulsar was discovered in 1967 by Jocelyn Bell and Antony Hewish. At first they were perplexed by the regularity of the pulses, and named their find LGM-1 which stands for little green men. Some thought that pulsars might be radio beacons from alien civilizations and it wasn’t until about a year later that astrophysicists were able to determine what was really going on.

Monday, November 1, 2010

Much has been written about quantum mechanics and how difficult—if not impossible—it is to grasp its true meaning. Niels Bohr, the Danish physicist who won a Nobel Prize in 1922 for his contributions to the understanding of quantum mechanics, said “Those who are not shocked when they first come across quantum theory cannot possibly have understood it.” Noted physicist Richard Feynman echoed this sentiment by saying “I think I can safely say that nobody understands quantum mechanics.”

Schrödinger's cat is placed in a sealed box with a flask containing a poison and some radioactive material. If the Geiger counter detects radiation the flask is broken and poison is released killing the cat. Quantum mechanics can be interpreted to say that after a while the cat is both alive and dead.

Erwin Schrödinger, famous for his thought experiment where a cat could be simultaneously alive and dead depending on the occurrence of a random quantum event, said this regarding quantum theory: “I do not like it, and I am sorry I ever had anything to do with it.” Considering that he won a Nobel prize in 1933 for his famed Schrödinger equation which is central to quantum mechanics, one would hope he was joking! The aspect of quantum mechanics that particularly bothered Schrödinger is called “quantum leaping”, where an electron instantaneously jumps from point A to point C without ever passing through point B.

Perhaps the biggest critic of quantum theory was Einstein, who jokingly said “Marvelous, what ideas the young people have these days. But I don’t believe a word of it.” Eventually he was convinced that it did indeed have merit, but even then it was his belief that the ability to understand what’s actually happening at the subatomic level exceeds the mental powers of physicists. In a 1926 letter to Max Born, Einstein wrote in reference to quantum theory “I, at any rate, am convinced that God does not throw dice.” In response, Bohr famously said, “Einstein, stop telling God what to do.”

Tuesday, October 26, 2010

How does one go about discovering a particle so small that nobody can see it? The British physicist J.J. Thomson won the Nobel prize in 1906 for doing just that—discovering the electron. At Cambridge University, Thomson was the epitome of an absentminded professor, sporting a tweed jacket, round-rimmed spectacles, mustache and dishevelled hair.

While exploring the nature of cathode rays, he discovered that he could deflect their path with an electric field. Measuring the amount of deflection under various strength fields, he was able to determine the mass of these particles, which he found to be about 1,800 times lighter than the hydrogen atom.

He called these particles “corpuscles,” and (incorrectly) suggested that they make up all of the matter in atoms. Most scientists at the time believed that the atom was the most fundamental unit of matter and indivisible, so to them this was a shocking concept.

The "plum pudding" model of the atom

Thompson proposed a “plum pudding” model for the atom, in which thousands of tiny, negatively charged corpuscles move about inside a massless cloud of positive charge. This theory was disproved by a former student of Thomson, Ernest Rutherford. By examining how alpha particles scattered after colliding with a thin sheet of gold foil, Rutherford found that the atom must have a small core, or nucleus. Rutherford proposed that the atom might resemble a tiny solar system, with a massive, positively-charged center orbited by electrons.

Rutherford's gold foil experiment

Luckily the name corpuscles did not stick or else today we would be going to corpuscular stores like Radio Shack, or reading c-mail instead of e-mail. Eventually the word electron gained favor. It comes from the Greek word for amber, which was known for its ability to electrostatically attract small objects when rubbed with fur.

Monday, October 18, 2010

Hidden away in a rugged and remote corner of eastern Utah lies one of the most unique archeological sites in North America—Range Creek Canyon. Native Americans known as the Fremonts lived there for several hundred years up until about 1,300 AD when their way of life came to a sudden and mysterious end. Similar to the Anasazi, the Fremonts were ancestors of today’s Pueblo peoples.

The site remains largely untouched today thanks to Waldo Wilcox. He is the rancher that owned the land and protected this secret for 50 years until he eventually sold it to the state of Utah in 2001. Currently, the land is under the care of the University of Utah’s Archeology Department.

A stone and adobe granary

The Fremonts hunted and farmed. They grew corn and stored it in stone and adobe granaries that they built in out-of-the-way cliff sides. Over 38 have been identified so far. These granaries are at many different elevations and often located in extremely precarious spots. It is thought that in lean years they stored their corn in higher, more difficult to reach areas in order to protect their limited food supply.

A Fremont petroglyph

They were also prolific artists, creating many carvings into the cliff walls (know as petroglyphs) and paintings in caves and on rocks (known as pictograms). Their cave dwellings were well crafted and a rich source of artifacts: pottery, stone tools, arrowheads and other items. This unique find will no doubt be carefully studied for years to come and promises to reveal many details of their lives.

1) True of false: Ranch Creek Canyon was home to the Fremont people a thousand years ago.

2) The Fremonts relied on the farming of ______________ which they stored in stone and adobe ______________________.

Sunday, October 10, 2010

NASA called Apollo 15 the most successful manned space flight ever achieved. It was the first moon mission to use the Lunar Rover which allowed the crew to travel greater distances from the Lunar Module than ever before, even though for safety sake they avoided traveling farther than they could safely walk back in case the rover broke down. They also collected 170 lbs. of moon rocks, one of them being the Genesis Rock. When later examined by geologists it was found to be 4.5 billion years old—meaning it was formed shortly after the creation of the solar system.

Genesis Rock

One of the experiments carried out during Apollo 15’s moon landing—called the hammer and feather drop—was done as a bit of theater to test the original Galileo theory that objects of different mass will fall at the same rate in a vacuum. In it, we see Mission Commander David Scott drop a hammer and feather at the same time form the same height to see if they both hit the ground at the same time. Since the moon has no atmosphere, it was the perfect place to carry out the experiment.

Hard to believe, but a significant portion of the population still does not believe that the Apollo landings really took place—that they were staged by NASA. One poll of 18 to 25 year old American revealed that 25 percent of them were not sure that the landings actually happened.As we have discussed before, one exception is all it takes to disprove a theory and I should think the hammer and feather drop would be enough to dispel this myth. But then again, some people still think Elvis is alive.
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